Electrophysiology catheters are commonly-used for mapping electrical activity in the heart. Various electrode designs are known for different purposes. In particular, catheters having basket-shaped electrode arrays are known and described, for example, in U.S. Pat. Nos. 5,772,590, 6,748,255 and 6,973,340, the entire disclosures of each of which are incorporated herein by reference.
Basket catheters typically have an elongated catheter body and a basket-shaped electrode assembly mounted at the distal end of the catheter body. The basket assembly has proximal and distal ends and comprises a plurality of spines connected at their proximal and distal ends. Each spine comprises at least one electrode. The basket assembly has an expanded arrangement wherein the spines bow radially outwardly and a collapsed arrangement wherein the spines are arranged generally along the axis of the catheter body.
It is desirable that a basket assembly be capable of detecting in as few beats as possible, including a single beat, as much of the electrical function of the region in which the electrode assembly is deployed, such as the left or right atrium. Through such mapping, it may be possible to identify areas of the heart generating abnormal impulses. For example, atrial fibrillation results from improper control of the timing and sequence of muscle contractions associated with a heart beat. Instead of regular, coordinated electrical activity, disorganized electrical signals may impede heart function. Suitable treatments may include performing an ablation procedure, such as targeted ablation of myocardial tissue to treatment the cardiac arrhythmias. A catheter may be used to apply RF energy and create a lesion to break arrhythmogenic current paths in the cardiac tissue. One type of an ablation procedure is termed pulmonary vein isolation, in which tissue in the area adjacent the junction of the pulmonary veins and the left atrium is ablated. The resulting lesions may isolate irregular electrical signals originating in the area from spreading through the rest of the atrium and disrupting the patient's heart beat.
For these and other applications, it would be desirable to provide a catheter and a technique for accurately positioning the mapping and/or ablation electrodes at the ostium of the pulmonary veins. Similarly, it would also be desirable to stabilize the portion of the catheter carrying the electrodes at the intended location. Moreover, it would be desirable to perform the mapping and ablation functions with a single catheter to simplify access to the treatment area. Accordingly, the techniques of this disclosure as described in the following materials satisfy these and other needs.